linux-kernel - Re: [Ksummit-discuss] bug-introducing patches

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Date:   Thu, 3 May 2018 11:55:29 -0700
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Al Viro <viro@...IV.linux.org.uk>
Cc:     Sasha Levin <Alexander.Levin@...rosoft.com>,
        "ksummit-discuss@...ts.linuxfoundation.org" 
        <ksummit-discuss@...ts.linuxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "w@....eu" <w@....eu>
Subject: Re: [Ksummit-discuss] bug-introducing patches

On Thu, May 03, 2018 at 07:20:39PM +0100, Al Viro wrote:
> On Thu, May 03, 2018 at 05:34:24PM +0000, Sasha Levin wrote:
> 
> > >Moreover, what the hell do you suggest in situation when
> > >	* foofs_barf() is b0rken in quite a few ways.  There's an
> > >easily triggerable memory corruptor that can be fixed locally as well
> > >as something else that needs a change of e.g. ->mkdir() calling
> > >conventions to take care of.  The change is mechanical and fairly
> > >simple, but it's already -rc4.
> > 
> > I'm not advocating to forcefully block people from submitting patches
> > after -rc4 (that was Ted's suggesting).
> 
> I am, though - change of a method signature when we have several dozens
> of instances does *not* belong in -rc5; if nothing else, it guarantees
> a nightmare pile of conflicts with individual filesystem trees.
> 
> > I'm just saying that as a maintainer, you should use your brain and
> > figure out how critical the bug is, how good is the fix and how well was
> > it tested, and decide if you want to merge it in or not.
> > 
> > If it fixed the bug and didn't introduce a regression, great! If it
> > messed something else, you'd have some input on how to address it better
> > in the future.
> > 
> > I'm trying to come up with a tool/system to help maintainers with
> > this task because right now it's not working too well. I'm not trying to
> > introduce arbitrary rules to make your life miserable.
> 
> And I am asking you what kind of rules do you want/expect/would prefer
> for Fixes: pseudo-header.  *I* do not give a flying fuck for its
> contents; I can put it in, if there is a good reason, though.  And
> the obvious consumers of that thing are -stable maintainers.  Including
> yourself.  Which is why I am asking you what should go in there in
> situation described above.  And no, that's not a rhetorical question;
> I really want to know.
> 
> Let me describe it again:
> 	* a bunch of holes is found in a function; all of them go back
> several years
> 	* a clean fix for the whole pile is a composition of
> 1) local fix of trivially triggered memory corruptor
> 2) tree-wide mechanical change of method signature + matching modifications
> of callers of that method (say, all five of them).
> 3) further changes in the function in question and its caller (which happens
> to be an instance of the method modified by (2).
> 	* dependencies between parts: (1) is standalone, (3) has a hard
> dependency on (2), (1) can be reordered past (2)+(modified 3), but modifications
> needed in (1) and (3) are not trivial.
> 	* the crap fixed by (1) is much more severe than that fixed by (3)
> (and (2) is an equivalent transformation which does not affect behaviour of
> anything).
> 	* too late in the cycle for tree-wide patches like (2).
> 
> As far as I'm concerned (and if it makes -stable folks' lives unpleasant,
> too fucking bad)

Don't care about me for stuff like this.  Fix it correctly and I'll
worry about any dependancy issues later :)

greg k-h